【正文】 及以上的配電裝置多采用屋外配電裝置。但110kv及以上的配電裝置，在嚴(yán)重污穢地區(qū)，如海邊和化工廠區(qū)或大城市中心,當(dāng)技術(shù)經(jīng)濟(jì)合理時(shí),也可采用屋內(nèi)配電裝置。成套配電裝置一般布置在屋內(nèi)，特點(diǎn)是結(jié)構(gòu)精密，占地面積小，建設(shè)期短，運(yùn)行可靠，維護(hù)方便，但耗用剛材較多，造價(jià)較高。目前我國(guó)生產(chǎn)的3—35kv各種成套配電裝置，在發(fā)電機(jī)和變電站中已廣泛應(yīng)用。第二節(jié)　高壓主接線配電裝置的布置一、主接線配置布置形式的選擇：電氣主接線配電裝置是發(fā)電廠的重要組成部分，是各種電氣設(shè)備及必需的輔助設(shè)備組成的，擔(dān)負(fù)著接受、分配和輸出電能的作用。根據(jù)高壓配電裝置設(shè)計(jì)的原則要求，并考慮本次設(shè)計(jì)的主接線電壓等級(jí)在系統(tǒng)中的地位以及出線回路數(shù)，參考《電力工程電氣設(shè)計(jì)手冊(cè)》規(guī)定，本次設(shè)計(jì)的變電站電氣主接線配電裝置的布置形式為：普通中型屋外型布置。即所有電器都安裝在同一水平面上內(nèi)，并裝在一定高度的基礎(chǔ)上，使帶電部分對(duì)地保持必要的高度，以便工作人員能在地面上安全活動(dòng)，中型配電裝置母線所在的水平面稍高于電器所在的水平面。二、普通中型屋外型布置形式的評(píng)價(jià)：優(yōu)點(diǎn)：普通中型配電裝置，國(guó)內(nèi)采用較多，已有豐富的經(jīng)驗(yàn)，施工、檢修和運(yùn)行都比較方便，抗震能力較好，造價(jià)比較低。缺點(diǎn)：占地面積較大，且由于斷路器單列布置，配電裝置的進(jìn)線會(huì)出現(xiàn)雙層構(gòu)架，跨線多，因而降低了可靠性。第三節(jié) 母線的選擇一、220KV系統(tǒng)母線的選擇：母線最大持續(xù)電流為：I＝()=220KV及以上室外高壓配電裝置，應(yīng)選用軟導(dǎo)線，并可根據(jù)負(fù)荷電流選擇導(dǎo)線截面。查《設(shè)計(jì)手冊(cè)》，應(yīng)選用LGJ500/35,其長(zhǎng)期允許截流量為1025A。選擇LGJ500/35大于LGJ300/30可不進(jìn)行電暈校驗(yàn)。二、：前面已經(jīng)敘述過發(fā)電機(jī)出口母線選用分相封閉母線，其母線的截面只需按長(zhǎng)期允許負(fù)荷電流來選擇。Igmax=(200x1000)/( )=8625A選用圓管形導(dǎo)線（銅材）查《設(shè)計(jì)手冊(cè)》，其型號(hào)為：D=280mm ,d=260mm,t=10mm,δ＝25mm，S＝7900mm2第七章 外語翻譯Vacuum Circuit BreakersVacuum switch provide another scheme for circuit interruption. In all our discussions so far we have considered the befavior of the gas between the parting contacts. This gas is ionized by several different processes and so provides free electrons, which move to the anode, and positeve ions, which move to the cathode. The positive ions ing to the cathode provide a mechanism by which electrons e out of the metal either thermionicallyorby high field emission. Practically all these phenomena disappear if the gas is removed from the space between the electrodes. The are is interrupted at the first current zero and dose not reignite. Vacuum breakers fail if lesks permit air to enter the interrupting chamber. The moving contacts are sealed by airtight metal bellow.Figure76(a)and(b) illustrate the construction of 3AF and 3AG vacuum breakers, respectively. The 3AF and 3AG vacuum breakers consist of three vacuum interrupters, their supports and the operating mechanism. The slimline design of the vacuum interrupters makes in possible to install the breakers in space saving swetching boards.When the contact separates,the current to be interrupted initiates a metalvapour arc discharge and flows through this plasma until the next current zero. The arc is the extinguished and the conductive metal vapour condenses withein a matter of microseconds. As a result,the dielectric strength in the break builds up very rapidly. The contact pieces are designed to generate a magnetic field which causes the arc root to rotate. The prevents their local overheating when interrupting large currents. In breakers for very high fault currents (50/63kA), an axial magnetic field ensures that the arc burns diffusely, at every current level,throughout the whole current range.The metal vapour arc discharge can only be maintained if a certain minimum current flows. A current that does not attain this level is chopped prior to current zero. This chopping current must be kept to a minimum in order to proevent unduly high overvoltages building up when inductive circuits are switched. The use of a special contact material ensures that current chopping is limited to 4~5A. Consequently the overvoltages are limited to uncritical values as well.The rapid build up of the dielectric strength enables the arc to be safely extinguished even if contact separation occurs immediately prior to current zero. The maximum arcing time for the last pole to clear is therefore only 15ms.The purpose of the arc quenching device of AC breakers is to deionize the break immediately after current zero. For all convertional arc quenching methods this means that the arc has to be booled even before the contact pieces have reached the minimum quenching distance and before the next current zero,a fact which automatically increases the arc energy. The arc drawen in the vacuum breaker, on the other hand , is not cooled since the metal vapour plasma is highly conductive and the resulting arc voltage only attains values between 20V and 200V. For this reason and because of the short arcing times, the arc energy developed in the bread is very small. This also accounts for the long service life of the vacuum breakers.The contact clearance in the interrupter need only be 6~25mm because under steadystate conditions a pressure of 109 bar suffices to obtain a high dielectric strength.真空斷路器真空開關(guān)提供了另一種電路開斷形式。迄今為止，在我們所有的討論中，我們都考慮分離接點(diǎn)間氣體的行為。氣體經(jīng)過幾個(gè)不同的過程被電離，產(chǎn)生了向陽極移動(dòng)的自由港電子和向陰極移動(dòng)的正離子。向陰極移動(dòng)的正離子使得電子由于熱離或強(qiáng)場(chǎng)發(fā)射而從金屬表面逸出。實(shí)際上，如果把氣體從電極間抽走，那么這些現(xiàn)象都不會(huì)發(fā)生。電弧會(huì)在第一個(gè)電流過零點(diǎn)被切斷而不會(huì)重燃。如果空氣通過裂縫進(jìn)入滅弧室，真空斷路器失靈。動(dòng)觸頭要被金屬波紋管密封在下面。真空斷路器是由三個(gè)真空斷續(xù)器失靈。他們的支架以及操作機(jī)構(gòu)組成。真空斷續(xù)器的細(xì)長(zhǎng)型設(shè)計(jì)使安裝斷路器開關(guān)柜可以節(jié)省空間。當(dāng)觸點(diǎn)分離時(shí)，將被斷開的電流激發(fā)金屬蒸汽電弧放電和流過等。離子體直至下一個(gè)電流過零點(diǎn)為止。然后，電弧被熄滅，導(dǎo)電的金屬蒸汽在幾個(gè)微秒內(nèi)冷卻。因此斷路器中介電強(qiáng)度恢復(fù)的非?？?。通過統(tǒng)計(jì)可使觸點(diǎn)元件產(chǎn)生使電弧固定旋轉(zhuǎn)的磁場(chǎng)。這可避免當(dāng)切斷大電流時(shí)產(chǎn)生局部過熱。在分?jǐn)嗦菲骼锎蟮墓收想娏鳎?0/63KA）時(shí)，軸向磁場(chǎng)可確保電弧擴(kuò)散燃燒。這發(fā)生在整個(gè)電流范圍內(nèi)的各個(gè)電流登記。要維持金屬蒸汽電弧，需要一定的最小電流。不能達(dá)到這個(gè)等級(jí)的電流過零點(diǎn)之前被切斷。為了避免當(dāng)電感電路被切換時(shí)而產(chǎn)生過高過電壓，斷續(xù)電流被限制在45A。因此，過電壓就可以被限制在正常值內(nèi)。由于介電強(qiáng)度的迅速恢復(fù)，使得在電流過零點(diǎn)之前發(fā)生觸點(diǎn)分離，也可以確保電弧的安全熄滅。因此，最后一個(gè)電極處熄滅的電弧也只要15MS。交流斷路器的滅弧裝置的目的是在電流過零點(diǎn)后去除離子，立即切斷線路。對(duì)于所有一般的滅弧方法，這意味著電弧不得不在觸點(diǎn)元件到達(dá)最短熄滅距離之前和電流再次為零之前被冷卻。這個(gè)現(xiàn)象將會(huì)自動(dòng)增加電弧的能量。另一方面，真空斷路器拉開的電弧不會(huì)被冷卻。因?yàn)榻饘僬羝入x子體是高導(dǎo)電的而且產(chǎn)生的電弧不會(huì)被冷卻。因?yàn)榻饘僬羝入x子體是高導(dǎo)電的而且產(chǎn)生的電弧電壓僅為20—200V。由于這個(gè)原因并且由于起弧時(shí)間短。在分?jǐn)鄷r(shí)，產(chǎn)生的電弧能量是非常小的。這使得真空斷路器的使用壽命很長(zhǎng)。由于在穩(wěn)態(tài)條件下，109bar壓力足夠獲得一個(gè)大的介電強(qiáng)度，所以在斷路器里，觸點(diǎn)間距只需6—25mm就可以了。參考文獻(xiàn)：各種電氣設(shè)備技術(shù)參數(shù)及價(jià)格（南京電力學(xué)校）電力系統(tǒng)設(shè)計(jì)手冊(cè)（中國(guó)電力出版社 電力工業(yè)部電力規(guī)劃設(shè)計(jì)總院編）電力工程電氣設(shè)計(jì)手冊(cè)（水利電力部西北電力設(shè)計(jì)院編）電氣設(shè)備（鄭州電力高等?？茖W(xué)校 郭琳編）火力發(fā)電廠設(shè)計(jì)規(guī)程 DL 5000—94（中國(guó)電力出版社 電力工業(yè)部華東電力設(shè)計(jì)院）繼電保護(hù)和安全自動(dòng)裝置技術(shù)規(guī)程各種電器設(shè)備技術(shù)參數(shù)及價(jià)格導(dǎo)體和電器選擇設(shè)計(jì)技術(shù)規(guī)定